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The Cape Canaveral Peninsula is the largest Holocene coastal sand deposit composed of beach ridges on the Atlantic coast of Florida. It is composed of 16 beach-ridge sets that are separated by erosional surfaces. Despite its prominence as a Holocene coastal depocenter, there are a limited amount of chronological data constraining the timing of its formation. In this study, we apply optically stimulated luminescence (OSL) dating on sand-sized quartz and radiocarbon dating on individual marine shells to develop a refined chronology of the Cape Canaveral beach-ridge plain with particular focus on constraining the depositional age of the northwesterly-most, and geographically oldest, beach-ridge set on the peninsula. We obtain an average OSL age of 5680 ± 240 years ( n = 4) for the initiation of coastal deposition at Cape Canaveral. The new ages, and the organization of beach ridges into 16 distinct sets indicates that the Cape Canaveral beach-ridge plain experienced an ~5700-year history of alternating deposition and erosion, with 75% of present-day Cape Canaveral (Beach-ridge Sets 5–16) deposited over the past 2000 years and Beach-ridge Sets 8–16 comprising 50% of the area over the past 1000 years. Because the minimum swale elevations of the ~5700-year Beach-ridge Set 1, and those of all the younger beach-ridge sets, are within several decimeters of present-day mean higher high water, we hypothesize that all the beach ridges present at Cape Canaveral could have been deposited at or within decimeters of present-day sea level. There is no evidence for Holocene “highstand” events over the past 5700 years in the published sea level curves from northeast and south Florida, which are based on subsurface estuarine foraminifera/leaf litter and mangrove peat data, respectively. This dichotomy illustrates the need to integrate both subaerial and subsurface data to produce a more realistic Holocene sea-level curve for the southeastern United States.

Gigantopithecus blacki was once a common primate during Early Pleistocene, distributed throughout southern China, but then it gradually declined with time and finally became extinct probably during Middle Pleistocene. Black Cave in Guangxi (the Zhuang Nationality Autonomous Region) was the first site yielding G. blacki teeth in-situ in 1956. It also produced numerous mammalian fossils belonging to the typical Middle Pleistocene Stegodon–Ailuropoda fauna from sediments overlying the G. blacki level. The present study carried out coupled ESR/U-series dating study of five Bovidae teeth from this palaeontological layer and obtained a weighted mean age of 383 ± 20 ka for this Stegodon–Ailuropoda fauna. This age estimate on fossil teeth is constrained by two 230 Th/U ages of 404 ± 24 ka and 382 ± 9 ka obtained on speleothems formed below and above the level of the Stegodon–Ailuropoda fauna. The Black Cave Stegodon–Ailuropoda fauna can be therefore correlated with MIS 11, and the remains of G. blacki should be older than 400 ka.

The Gault Site, Texas, U.S.A., affords a near-complete regional prehistoric sequence from an ~ 2 m-thick alluvial sedimentary interval. Age estimates on Clovis, Late Paleoindian, and Archaic components were obtained using optically stimulated luminescence (OSL) dating of silt-sized quartz grains. The luminescence characteristics of the quartz are favorable, showing normal equivalent dose distributions and no evidence of incomplete zeroing. The artifacts span Clovis to Archaic forms, and their ages are generally in excellent agreement with independent radiocarbon ages from five other Texas sites. The mean OSL age of the Clovis deposits of 12,900 ± 700 a agrees with the known Clovis ages from Central Texas and a generalized model that places the Clovis occupation of Central Texas between ~ 13,600 to 13,000 cal BP (Holliday, 2000). This study indicates that accurate age determinations can be made using OSL on silt-sized quartz grains at Gault.

Human presence in North America before ~16 thousand years ago is confirmed by age measurements from Area 15 of the Gault Site., American archeology has long been polarized over the issue of a human presence in the Western Hemisphere earlier than Clovis. As evidence of early sites across North and South America continues to emerge, stone tool assemblages appear more geographically and temporally diverse than traditionally assumed. Within this new framework, the prevailing models of Clovis origins and the peopling of the Americas are being reevaluated. This paper presents age estimates from a series of alluvial sedimentary samples from the earliest cultural assemblage at the Gault Site, Central Texas. The optically stimulated luminescence age estimates (~16 to 20 thousand years ago) indicate an early human occupation in North America before at least ~16 thousand years ago. Significantly, this assemblage exhibits a previously unknown, early projectile point technology unrelated to Clovis. Within a wider context, this evidence suggests that Clovis technology spread across an already regionalized, indigenous population.

Optically stimulated luminescence (OSL) has been employed successfully to determine the ages of palaeosols from earthen mounds in the southeastern USA, providing archaeologists with a means of dating monument construction in the absence of carbonaceous materials and geologists with a setting for understanding factors that can affect the luminescence intensity (i.e., burial dose) of soils. However, OSL dating has not been adequately tested on mounds whose principal component is sand, shell, or a combination of these two, despite the fact that monuments composed of such materials are common to the coasts and interior coastal plains of the region. Radiocarbon dating of bone collagen and soil-carbon and OSL dating of quartz grains extracted from the fill of mounds at the Crystal River and Roberts Island sites on the west-central coast of Florida, USA are used to determine the timing and history of mound construction at the sites. Comparison of OSL and radiocarbon ages on materials from the same or closely related contexts provides insight into factors influencing age determinations in mound fill deposits, particularly the type of construction material (sand or shell) and the manner in which these were deposited. The results contribute to the understanding of the temporal context of platform mound construction in southeastern USA.

For the first time, electron spin resonance optical dating (ESROD) has been conducted on littorally transported and aeolian siliciclastic sediments in Florida. ESROD utilizes light-sensitive radiation-sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time-dependant signal. These defects saturate at higher levels of radiation dose, compared to optically stimulated luminescence, and therefore extend the optical dating range back into the millions of years. Our results show that the Trail Ridge Sequence is a multi-depositional unit that began deposition around 2.2 Ma and continued until 6 ka. The Osceola Cape, of the Effingham Sequence, was deposited around 1.5 Ma, and the Chatham Sequence was a multi-depositional terrace with at least three events preserved.

Ground penetrating radar and single-aliquot regenerative-dose optically stimulated luminescence were used to determine the depositional environments and age of unconsolidated siliciclastic sediments near Apalachicola, Florida. Five direct-push cores, five vibracores and 28 optically stimulated luminescence samples were collected, as well as 7 km of ground penetrating radar data. A new model of cosmic dose rate calculation, which removes the effect of a much younger aeolian cap, was utilized to calculate more representative optically stimulated luminescence ages. Five radar facies were identified based on reflector amplitude and orientation. The resulting data indicate that the Tertiary/Quaternary Shelly Sediments were deposited before marine isotope stage 6, the Quaternary Alluvium was deposited during marine isotope stage 6 and the Quaternary Beach Ridge and Dune was deposited during the marine isotope stage 5e sea-level highstand, which peaked at approximately 2·5 m above present sea-level in this area.

article i nfo Vertical sediment cores in five separate beach ridge complexes along the north-east Gulf of Mexico Coast were recovered and dated using optically stimulated luminescence (OSL) dating of quartz: these are located on Cape San Blas (CSB), Little St. George Island (LSGI), Richardson's Hammock (RH), St. Joseph Peninsula (SJP) and Saint Vincent Island (SVI). All of these landforms are coastal barrier systems situated along a 100 km stretch of the Florida Panhandle, U.S.A. Two samples were collected for dating from each core. Ridge accumulation rates (RAR) associated with lateral progradation were calculated from the dated samples. We also determined average sediment accumulation rates (ASAR) for two intervals within each sediment core. All OSL ages within the sediment cores were found to be in stratigraphic order or in a few cases statistically indistinguishable. Moreover, all dated ridges were found to be in correct temporal sequence based on their geomorphic positions. Rapidly accreted sequences were found to be backed by St. Joseph Bay in the western region of the study area. More slowly accreted sequences were associated with the more eastern stretches of the study area backed by St. Vincent Sound and Apalachicola Bay. Our ASAR results are in accord with an Australian study of modern dune accumulation. Perhaps our most important finding is that in the barrier island environments of this north-eastern Gulf Coast region, aeolian sedimentation continues well after full vegetative cover develops and stranding of landward ridges takes place. This confirms our similar earlier observation on SVI (Lopez and Rink, 2008). We find that up to approximately one order of magnitude lower sedimentation rates occur after an initial period of more rapid aeolian accumulation for the vertical intervals studied in foredune ridges. Lateral progradation rates of ridge sequences were highly variable within the study area, ranging from 92 to 848 m/100 years, but we did find agreement between some of our slower ridge accumulation rates and those in other areas of Florida and around the world determined using OSL and 14 C dating. We conclude that OSL may be used in a regional context to establish variation in progradation rates and aeolian accumulation that varies among systems.

A robust timeframe for the extant cave deposits at Liang Bua, and for the river terraces in the adjoining Wae Racang valley, is essential to constrain the period of existence and time of extinction of Homo floresiensis and other biota that have been excavated at this hominin type locality. Reliable age control is also required for the variety of artifacts excavated from these deposits, and to assist in environmental reconstructions for this river valley and for the region more broadly. In this paper, we summarize the available geochronological information for Liang Bua and its immediate environs, obtained using seven numerical-age methods: radiocarbon, thermoluminescence, optically- and infrared-stimulated luminescence (collectively known as optical dating), uranium-series, electron spin resonance, and coupled electron spin resonance/uranium-series. We synthesize the large number of numerical age determinations reported previously and present additional age estimates germane to questions of hominin evolution and extinction.

Pleistocene faunas from south China are difficult to subdivide based on the long temporal ranges of many taxa and a reduced number of genera in comparison to faunas from temperate north China. In south China, theAiluropoda–Stegodonfauna is a very general one and includes a relatively stable suite of genera that apparently persisted for long periods of time. These attributes have made constraining its time range difficult. Application of electron spin resonance (ESR) dating of tooth enamel constrains the ages well where uranium uptake was minor. Where uranium uptake into teeth was significant, an approach combining ESR and230Th/234U isotopic analysis also yields excellent ages. Previous estimates of early, middle and late Pleistocene time ranges previously determined by biostratigraphic seriation for theAiluropoda–Stegodonfauna are confirmed in all cases but are made more precise with our approach, including specific time ranges for certain archaic taxa. Absolute dating also yields an extended time range forGigantopithecus blackiof 1200 to 310 ka.

Optical dating of quartz by optically stimulated luminescence has a time range that is generally less than about 500 ka, due to relatively rapid saturation of the available luminescence defects in quartz. We test here a new method, electron spin resonance (ESR) optical dating of quartz, in which radiation-sensitive defects at aluminum and titanium atoms on silicon sites give rise to signals which can only be detected near liquid nitrogen temperature and which have a much higher capacity to absorb radiation dose before saturating than optical luminescence-detected signals. Our results show this method yields agreement with independent age control out to about 2.5 million years, extending here the dating range of optically exposed quartz in sediments in along-shore sediments (aeolian and waterlain) by a factor of about 5. Three sites in along-shore lacustrine and marine aeolian environments yielded very good agreement with independent age control. Details of single saturating exponential fitting in relation to agreement with expected burial doses and annealing of Al and Ti signals provide additional data to consider the best approaches to the dating method. Furthermore, we propose a new criterion for ESR optical dating: both the Al signal and Ti signal ages must agree to insure accurate burial ages. Moreover, when Al signal ages are lower than Ti signal ages, then the Al signal may be taken as the minimum burial age.

The Pech-de-l'AzeI skull and mandible are included in the juvenile Neandertal remains from Europe. However, some preserved features in the cranial skeleton seem to distinguish the specimen from other Neandertal children. Unfortunately, the stratigraphic position and dating of this child has never been clear. Our recent work on unpublished archives show that the Pech-de-l'AzeI Neandertal child was discovered at the bot- tom of layer 6, attributed to the Mousterian of Acheulean tradition type B. These skull and mandible are the first diagnostic human remains (aside from an isolated tooth) attributed to the Mousterian of Acheulian tradition (MTA) type B. Consequently, we confirm that Neandertals were the makers of this Mousterian industry, which is characterized by unusual high frequencies of Upper Paleolithic type tools, elongated blanks and blades. We were able to date the context of the hominid remains by dating layer 6 and the layers above and beneath it using ESR, coupled ESR/ 230 Th/ 234 U (coupled ESR/U-series), and AMS 14 C. Coupled ESR/U-series results on 16 mammalian teeth constrain the age of the uppermost layer 7 to 41e58 ka, and layer 6 to 37e51 ka. The wide spread in each age estimate results mainly from uncertainties in the gamma-dose rate. These ages are concordant with AMS 14 C ages of two bones coming from the top of layer 6, which provide dates of about 41.7e43.6 ka cal BP. A combination of stratigraphic arguments and dating results for layers 6 and 7 show that the Neandertal child cannot be older than 51 ka or younger than 41 ka. The lowermost layer 4 is shown to be older than 43 ka by the principle of superposition and ESR dating in the immediately overlying layer 5. This study shows that the MTA type B had been manufactured by Neandertals before the arrival of anatomically modern humans in the local region. Additionally, by providing a firm chronological framework for the specific mor- phometric the features of Pech-de-l'AzeI Neandertal child, this study is a new step toward the understanding of temporal and spatial changes in the ontogenesis of Neandertals in south-western Europe during oxygen isotope stages 5e3.

Liang Bua, a limestone cave in western Flores, has an archaeological and faunal sequence known to span the last 95 ka and is the type-site for a small-bodied hominid species, Homo floresiensis. This paper describes the geomorphic history of this significant site, and presents numerical ages for key events as determined by thermo luminescence dating of sediments (using a dual-aliquot regenerative-dose protocol) and uranium-series dating of flowstones. Our age estimates indicate that Liang Bua existed as a subterranean chamber by 400 ka ago. It was subsequently exposed by the incision of the Wae Racang River, which invaded the cave around 190 ka and deposited an upward-fining sequence of water-rolled boulders and cobbles. The latter conglomerate was partially reworked around 130 ka ago and was capped by flowstones at 100 ka. The conglomerate also contains stone artefacts, which implies that the occupation of the surrounding area is at least as old as the time of emplacement of the conglomerate. After 190 ka, a complex sequence of erosion and deposition led to the accumulation of at least 11 m of sediment in the front chamber of the cave, which proved suitable for hominid occupation. Such geochronological and geomorphological information is extremely valuable for interpreting the archaeological record at Liang Bua and its wider significance. (c) 2006 Elsevier Ltd. All rights reserved.

The Nasca lines are geoglyphs – arrays of stones forming geometric shapes constructed by ancient humans, the largest ones occupying areas of more than 1km2. The authors used optically stimulated luminescence dating of quartz buried when the stone lines were constructed to give new dates for contexts associated with geoglyphs on high mesetas near Palpa. They conclude that the stone lines at sites at San Ignacio and Sacramento were constructed between AD 400 and 650. This suggests that they were made in the later part of the Early Intermediate Period by people of the Nasca culture.

Electron paramagnetic resonance (EPR) biodosimetry of human tooth enamel has been widely used for measuring radiation doses in various scenarios. We have now developed EPR dosimetry in tooth enamel extracted from canines. Molars and incisors from canines were cleaned by processing in supersaturated aqueous potassium hydroxide solution. The dosimetric signal in canine tooth enamel was found to increase linearly as a function of laboratory added dose from 0.44±0.02 to 4.42±0.22 Gy. The gamma radiation sensitivity of the canine molar enamel was found to be comparable to that of human tooth enamel. The dosimetric signal in canine enamel has been found to be stable up to at least 6 weeks after in vitro irradiation. A dosimetric signal variation of 10–25% was observed for canines ranging from in age 3 years to 16 year old.

The dosimetric response of neutron irradiated human tooth enamel has been investigated using electron paramagnetic resonance (EPR) dosimetry. Continuous energy fast neutrons of mean energy less than 450 keV were produced from the McMaster University 3 MV K.N. Van de Graaff accelerator employing a thick lithium target via 7 Li(p,n) 7 Be interaction. Prior to its use for various experiments, the gamma dose contamination of the neutron beams was determined at the selected proton beam energies using the tissue-equivalent proportional counter (TEPC). The neutron sensitivity (/Gy-100 mg) of human tooth enamel remained constant for various mean neutron energies ranging from 167 to 450 keV. Similarly, the EPR signal intensity remained independent of the neutron dose rate variation from 0.5 to 2.4 Gy/h.

Electron spin resonance (ESR) analysis was done on teeth excavated at Hayonim between 1993 and 1997. 230 Th/ 234 U analysis was done on two of these teeth and one calcite speleothem excavated in 1992. Small amounts of uranium uptake into teeth provided nearly ideal conditions for ESR age determinations. The combined ESR/ 230 Th/ 234 U analyses on teeth confirmed that uranium uptake occurred according to values constrained by early (EU) and linear (LU) uptake ESR model age estimates, suggesting that EU and LU ESR model ages on other teeth were reliable burial ages. A speleothem stratigraphically above all the teeth yielded a 230 Th/ 234 U age of 155.3± 2.9 1.4 ka. The EU and LU ESR mean model ages for teeth in layers just below the speleothem were 177±12 and 182±15 ka respectively. Teeth in the lowest part of the section in the Central Area yielded younger ages, apparently due to the increase in radioactive potassium content associated with the formation of siliceous aggregate mineral assemblages nearby. These results were rejected. The ages of the reliably dated portion of the section were contemporaneous with levels at Tabun Cave containing both Tabun C-type and D-type lithics, but they were significantly younger than the levels at Tabun which contain only the D-type lithics. The use of infrared spectroscopy to identify mineral assemblages in close proximity to teeth were important to be able to select only those teeth not affected by changes in radioactive dose rate through time.

The important Lower and Middle Palaeolithic site of Tabun has been previously dated using ESR, U-series and TL. ESR ages throughout the site are substantially younger than TL dates, although these methods have been shown to agree at other sites in Israel and elsewhere. All previous ESR dates have been obtained on museum specimens using only attached sediments for dosimetry. Here we report the first ESR and U-series analyses of a tooth found in situ in an area equivalent to the lowest part of layer Ed. We obtain a combined ESR/U-series age of 387+49−36ka, in good agreement with a TL age of 340±33 ka for similar levels, and substantially older than an ESR/U-series age using attached or nearby sediment for dosimetry. We conclude that the most likely explanation for the previous shorter ESR chronology was the use of inappropriate gamma dose rates based on sediments attached to teeth.

Apatite veins exposed at Tabun Cave were collected for an electron spin resonance (ESR) dating feasibility study. The dose response and thermal stability of the ESR signals were found to be suitable for an age determination using a signal at g=2.0015. The early and linear uptake ESR ages were found to be in the range of 45–75 ka. Since the apatite vein is known to have crystallized in situ after the formation of the host sediments, the age was expected to be younger than that of the host sediments. Thermoluminescence dating of heated flints (J. Archaeol. Sci. 22 (1995) 495) in corresponding units establish the age of the host sedimentation to be 306±33 ka or greater. The apatite veins ages were found to be at least 200 ka younger, consistent with their expected younger age. We emphasize that these results are not relevant to a resolution of the controversy that remains in the literature regarding the burial ages of sediments at Tabun Cave. The significance of this dating approach is discussed in relation to diagenesis of bone and guano, which is important to our understanding of cave sediment formation and to the determinations of sediment ages using other radiation exposure techniques.

Parameters of OSL components of quartz in volcanic ashes and in tephric loess from Japan were determined, and their characteristic in terms of recuperation was investigated. As a result, the medium and slow1 components, which were the main components in the volcanic quartz, were also found in the quartz in tephric loess, while the OSL of quartz in tephric loess was dominated by fast component. This suggests that the medium and slow1 components in tephric loess are probably coming from volcanic quartz. All the components in volcanic quartz appeared to give strong recuperation after preheating. In order to date tephric loess, the separation of fast component was essential, because only negligible recuperation was observed in the fast component. The equivalent dose ( D e ) of tephric loess decreased significantly with the illumination time, while recuperation increased with illumination time. A plot of D e versus recuperation indicated that D e decreased exponentially as recuperation increased. Since the fast component is free from recuperation, the extrapolation of the exponential curve to the point that recuperation equals zero gives D e , which entirely utilizes fast component. The agreement of the OSL ages with independent ages using the corrected D e values provides strong evidence for the validity of the correction method.

To study the neutron response of human tooth enamel, a number of experiments with an accelerator-based neutron source have been designed. The neutron beam was produced with the low gamma yield, 7 Li (p,n) 7 Be type thick target, using the 3 MV McMaster K.N. Van de Graaff accelerator. The dosimetry was done using a pre-calibrated snoopy type neutron dosimeter. Neutron irradiation induces a dosimetric signal in the tooth enamel at the same defect site as gamma produced damage with the same g -values ( g || =1.9973, width 0.4 mT g ⊥ =2.002 , width 0.3 mT ). The dosimetric signal grows linearly with neutron dose from 6– 35 Gy tissue dose. Dosimetric response in two different grain sizes (300– 500 μm , and grains mm ) has shown increased dosimetric amplitude in the larger grains. Dose build up effect on tooth inside the mouth due to cheek was simulated by placing a 4 mm thick paraffin wax layer between the beam and tooth, but had little effect. These results show that for mean neutron energy of 280 keV , the relative neutron response of the human tooth enamel ranges from 8% to 12% of the equivalent gamma ray response.

Three sediment samples were collected from a soil profile at the Lagoa do Bordoal site, Algarve, Portugal. Quartz extracted from soil horizons within the profile, was optically dated using the single-aliquot regenerative-dose (SAR) protocol outlined by Murray and Wintle (Radiation Measurements 5 (2000) 523). The optically stimulated luminescence (OSL) emitted by quartz within the 90–150 μm size range was measured using three aliquot sizes. The equivalent doses ( D E ) that were obtained show an asymmetric distribution. As the numbers of grains in each aliquot are reduced, the distribution of doses is clearly shifted to lower D E values including zero doses on single grain aliquots. This shift is accompanied by an increase in the asymmetry of the distribution. These patterns indicate that as the aliquot size decreases, the distributions are increasingly characterized by aliquots with lower D E 's. With respect to the present day modern surface, this shift is most evident in the sample collected from a depth of 37 cm, within an ancient B-horizon. It is least evident in the sample located only 10 cm below it, within a sand unit. An asymmetric distribution of D E 's can be a result of a large number of grains that were well bleached at burial being mixed with a small number of grains that were partially bleached at that time (Radiation Measurements 30 (1999) 207). However, the shift in D E 's that is seen in the Lagoa East samples is most likely due to the postburial downward movement of fully and partially bleached grains from the surface, with possible contributions from the downward movement of grains that received low doses while buried in overlying horizons. The simplest explanation for our results is that grains carrying zero or small D E 's have been moved downward during bioturbation events. These results suggest that downward bioturbation in ancient soil profiles can be identified based on the OSL characteristics of quartz grains. We are also able to provide a minimum age of 24.4±3.2 ka for the Upper Palaeolithic lithic assemblage at the site.

A small portion of the Early Levantine Mousterian site of Rosh Ein Mor site was re-excavated in 1996, in order to recover ostrich eggshell for uranium series dating analyses. Flint that appeared to have been heated was recovered from the archive at Southern Methodist University, and tested for its feasibility for thermoluminescence dating. Flint and eggshell were dated and found to give significantly different results. The eggshell yielded a mass spectrometric 230 Th/ 234 U burial age of 200·9+9·5/−8·7 ka, while the flint showed a range of last heating ages between 14 and 48 ka. These ages are compared with other age estimates for sites containing similar lithic industries in the region. We conclude that the eggshell age is most likely the minimum age of the time of occupation in which the Early Levantine Mousterian industry was produced, and that the flint heating ages represent either later ephemeral occupations with anthropogenic heating of the flints, or natural fires in which tree roots heated the flints. The results, taken together with other age estimates for the Early Levantine Mousterian in this area, suggest that while in the central Levant we find its earliest appearance between 225 and 300 ka, in southern Israel we find no correspondingly early ages.

Electron spin resonance (ESR) dating has been carried out on ungulate tooth enamel samples from the Pleistocene deposits of Mugharet el ‘Aliya, Atlantic coastal Morocco. Age estimations for wave-induced breaching of the cavity and initial sand deposition (Layer 10) are 62±6 ka bp by the Early Uptake (EU) model and 81±9 ka bp by Linear Uptake (LU). Samples from Aterian occupations in Layers 5 and 6 and a possible occupation in Layer 9 yielded EU estimated ages between 39±4 and 44±5 ka bp and LU ages between 47±5 and 56±5 ka bp . Incorporating the entire range of EU and LU model ages, the Aterian occupations are dated to between 35 and 60 ka bp . When compared with the published, mostly radiocarbon-based ca. 40–20 ka bp chronology for the Moroccan Aterian (e.g., Debenath, 1992), these new results imply an Aterian arrival or Mousterian-to-Aterian transition occurring beyond the upper limit of the radiocarbon method.

Optically stimulated luminescence (OSL) was used to date glacial sediments to elucidate the ages of past glacial advances in Kanchenjunga Himal, eastern Nepal. Seven glacial sediments samples were collected from four different moraines, and quartz grains were extracted from samples. However, the luminescence from feldspars existing as minor contamination and/or microinclusion in the quartz grains was so bright it masked the quartz signal. After etching the fraction 20 min extra with HF, the natural infrared stimulated luminescence (IRSL) signal, which indicates the existence of feldspar, almost disappeared. Equivalent dose (DE) values were estimated by the single aliquot regenerative-dose protocol, using two different quartz fractions: fraction A, which was etched 20 min extra, and fraction B, which was prepared by the standard procedure still had a strong feldspar signal. Although the natural IRSL intensity for fraction A was so weak, the regenerated IRSL was relatively strong and not negligible for most of the aliquots. Such aliquots were omitted because the sensitivity of the feldspar is much higher than quartz and the difference in the sensitivity can cause DE underestimation. Out of 42 aliquots from four samples for fraction A, only six aliquots from two samples were remained. The DE values for single aliquots were uniformly distributed for fraction B. Moreover, the calculated OSL ages for fractions A and B from the two samples agreed with each other. It is suggested that both quartz and feldspars grains or microinclusions in quartz grains were likely to have been bleached, while glacial debris has been transported on the glacier. The resulting OSL ages suggest that the glaciers expanded at 5–6, 8–10, and 20–21 ka in the Kanchenjunga Himal.

The intensity of an ESR signal associated with oxygen vacancies in quartz (E1′ center and heat-treated E1′ center) are correlated with the radiometric age of their host rocks. Two natural processes are responsible for the production of oxygen vacancies (1) lattice damage along alpha recoil and alpha particle tracks and (2) randomly distributed ionization damage from energetic electrons (beta particles) and gamma photons. The aim of this paper was to determine whether the track damage process is dominant relative to the ionization processes. Heat-treated E1′ centers are considered a proxy measure of the oxygen vacancy concentration. In situ alpha irradiation of quartz was accomplished by neutron irradiation of lithium and boron-bearing quartz. We found that the oxygen vacancy population measured by ESR was a factor of 2 higher than estimated from calculations of the damage using Ziegler's TRIM software. Considering the uncertainties in absolute determinations of spin concentration from ESR signals, the agreement is very good and supports the theory that alpha particle damage is largely responsible for oxygen vacancy production during natural irradiation of quartz over intervals of hundreds of millions of years.

Properties of E′ centres of high geological age in flint from different locations have been studied. ESR spectra of γ -irradiated samples of heated and unheated Silurian and Eocene flint show thermally unstable components. The spectrum of one species could be simulated using the g values: 2.00164, 2.00059, and 2.00046. Two others deliver ESR-signals at g =2.0015 and 2.0012, respectively. These unstable components cannot be identified with any known E′ centres. About 50% of the ESR intensity of the E′ centres in unheated flint induced by artificial γ -rays is thermally stable. This effect is probably due to a steady state and might be useful for dating of unburned flint tools (“skinflint dating”).

We examined the natural residual thermoluminescence (NRTL) of quartz in samples collected from the surface and the subsurface of the beach on a sand spit in the Gulf of Mexico located at St. Joseph Peninsula State Park near Apalachicola Florida. The subsurface samples were collected within two berm structures that respectively, represented a hurricane deposit and a subsequently deposited smaller tidal berm (beach ridge) produced by wave action during a seven-week period following the storm. Higher NRTL was found in the underwater zone of the beach surface than in the areas exposed to full daylight on the beach and in the dunes (seawater is known to strongly absorb the ultraviolet component of daylight). In each of the berms, similar variations in NRTL could confidently be correlated to primary sedimentary structures. Strong transitions in NRTL occurred at boundaries between sedimentary units. These variations were used to interpret processes of berm formation and the identity of local sources of quartz incorporated into the berms.

Samples taken from four different faults at a depth of 400 m show no sign of a bulk heating higher than about 350°C (heating time 15 min) during fault activities. Besides radiation defects, the aggregation behavior of iron ions studied by electron spin resonance (ESR) can be used as a measure for the thermal history of fault gouge material. Clusters of iron ions are formed as a result of the heating of biotite and feldspar minerals. They give broad (ΔB ≈ 200 mT) and intense signals in the ESR spectra. Mn2+ point defects react very sensitively to crushing of the samples, while relatively isolated and coupled Fe3+ point defects in the feldspars do not.

A wide range of potential dating methods may be applied to archaeological deposits found in caves and rockshelters, depending on the nature of the deposit and age range of the deposit. Organic sediments, including faunal and floral material, can be dated by radiocarbon (AMS and high-sensitivity beta-counting). Many karstic features contain speleothems which can be dated with high accuracy by U-series. Wind-blown detritus, where it is the dominant constituent of the cave deposits, can be dated by luminescence (TL, OSL, or IRSL), taking care to avoid material fallen into the deposits from the shelter/cave walls. Fireplaces contain burned rocks (including stone artifacts) which can be dated by TL. Enamel from the teeth of mammals is present in most sites, representing either animal residents of the shelter, or residues from food brought to the shelter by human residents. Electron spin resonance (ESR) dating of enamel is applicable over a wide time range, with high accuracy and reasonable precision where uranium accumulation in teeth is low, but with lower precision where uranium content in teeth is high. In general, multiple dating methods applied to a site may resolve ambiguities arising from uncertain model assumptions in some dating methods. © 2001 John Wiley & Sons, Inc.

The effect of crushing on the TL and OSL signals in quartz was investigated to examine the feasibility of using OSL and TL for dating of faulted rocks. 275°C TL signals were not reduced by crushing by hand (mortar and pestle), in a pellet die press, or using an automatic mortar and pestle, but the sensitivity of the 100°C TL signal to a test dose decreased in crushed samples. Green light-stimulated OSL signal intensities were not decreased after crushing, but showed strongly increased inter-aliquot variability after crushing. We concluded that OSL and TL in quartz might be useful to characterize the crushing history of quartz in fault rocks, but their usefulness in dating fault events was not evident because we did not find evidence of signal zeroing under the conditions used in this study.

New results describing gradients in effective alpha and beta doses within a layer of tooth enamel in planar geometry are presented. The alpha (track) dose to an enamel layer is calculated using an algorithm similar to that of Aitken (Aitken, M.J., 1987. Alpha dose to a thin layer. Ancient TL 5, 1–3.). The code for ROSY version 1.4 ( Brennan, B.J., Rink, W.J., Rule, E.M., Schwarcz, H.P., Prestwich, W.V., 1999. The ROSY ESR dating software. Ancient TL, in press. ) incorporates this algorithm. The approach allows for variation of the alpha track dose near the edges of the enamel, and we describe the gradient of the alpha track dose within 40 μm of each edge of the enamel for natural sources. In ESR or luminescence dating of naturally thin layers, for which stripping of the surface layer containing the alpha dose gradients may not be feasible, age estimates may change by as much as 5–10% when the detailed alpha dose calculation is included. Modern Monte Carlo-based results for the variation of beta dose for depths up to 2 mm are compared with ROSY results. For external irradiation by different sources, the attenuation of the ROSY dose estimate with depth is usually less rapid than that of the Monte Carlo-based estimate. The ROSY estimate of average beta dose to a layer in this case is between 5 and 18% higher than the Monte Carlo estimate.

Thermoluminescence (TL) dating of burnt silex (flint, chert), electron spin resonance (ESR) dating of teeth and 14 C-accelerator-mass-spectrometry (AMS) dating of bones has been carried out on samples from the Late Middle Palaeolithic and Early Upper Palaeolithic levels of the Geisenklosterle Cave, South Germany. ESR dating on tooth enamel from the upper part of level IV, which contains a very small undefined Middle Palaeolithic assemblage, yields a mean age of 43·3±4 ka. The overlying Early Aurignacian (level III) is placed in the Hengelo Interstadial by palaeoecological analysis. 14 C-AMS results give a mean age of 38·4±0·85 ka, whereas a mean age of 40·2±1·5 ka is obtained by TL of burnt silex, confirming the correlation of the Early Aurignacian level with the Hengelo Interstadial in Oxygen Isotope Stage (OIS) 3. 14 C-AMS of bone samples from the Aurignacian (level II) resulted in a mean age of 33·5±0·35 ka, whereas the TL ages on burnt silex are again older at c . 37 ka. These TL results can be taken as an indication of the age underestimation by 14 C caused by the lack of calibration. The Aurignacian level contains some of the most elaborate symbolic representations from the Upper Palaeolithic. Artwork of comparable quality is radiocarbon dated to 31,000 ka at the Grotte Chauvet, thus being significantly younger. Furthermore, the Geisenklosterle Cave provides evidence of the existence of early rock art in Central Europe, although only small pieces survived erosion. The Gravettian assemblage of the Geisenklosterle Cave yielded a mean 14 C-AMS age of 29·0±0·25 ka.

Two experiments were performed to determine the distribution of beta dose in a target medium as a function of distance from a planar source (2 π geometry). In Experiment ♯1 planar absorbers were used to simulate depth in the target medium, and the attenuated dose that penetrated the intervening absorbers was detected using thermoluminescence from CaSO 4 :Tm. In experiment ♯2 pellets of powdered tooth enamel were situated in a cavity in solid tooth enamel. Dose response of the electron spin resonance (ESR) signals in the pellets allowed direct detection of dose distribution within the target medium. The dose distributions were found to agree more closely with Monte Carlo calculations and with one-group transport theory ( Prestwich et al., 1997 and Brennan et al., 1997 ) than with approximations used widely in ESR dating applications ( Grun, 1986 ). Although the latter were supported by experiments by Aitken et al. (1985) , the results of experiment ♯1 provided data to suggest that departure from 2 π geometry was unacceptably large in the Aitken et al. (1985) configuration. The beta doses obtained by one-group theory in typical target volumes of enamel were 17 to 40% lower than those obtained using the Grun approximation. It was concluded that one-group transport theory provides the best available routine tool for calculations of beta dose attenuation in near-planar target materials (e.g. tooth enamel and shell) irradiated by natural sources, although Monte Carlo methods are better and could eventually be introduced into the ROSY ESR dating program ( Brennan et al., 1997 ). It was also concluded that a revision of previously published ESR ages using one-group transport for beta dosimetry will be needed. For cases where the U concentrations in enamel are generally low (less than a few ppm), previously published ESR ages on tooth enamel are systematically too young by 5–30%.

The scope of application of ESR spectroscopy has greatly expanded with the advent of its widespread use in radiation exposure dating around 1980 and its use in retrospective dosimetry since the Chernobyl disaster in 1986. Few fields of study are of such breadth that they span topics as diverse as dating of human origins, volcanic activity, cave deposits and earthquakes, while also providing prognoses for radiation accident victims. Between 1945 and 1975 ESR was mainly used to define the nature of paramagnetic defects in crystalline and amorphous materials, which laid the foundation for its use in applied areas in Quaternary geology, archaeometry and accident dosimetry. This review chronicles the development of the use of ESR in applied science since 1975, with particular emphasis on the state of the art in the period 1987–1997. The first part of the review focuses mainly on the range of applications for datable materials: tooth enamel (Section 2), calcite (Section 3) and quartz (Sections 4–9), while the second part comprises the areas of retrospective dosimetry (Section 10) and new applications (Section 11). The review concludes (Appendix A) with an introduction to the physical basis and assumptions involved in ESR dating, and compilations of valuable reference works for students and workers in this field.

Sediments filling the cave of El Castillo, in Cantabrian Spain, contain Acheulian, Mousterian, and Upper Palaeolithic industries. Bischoff et al . (1992) obtained a U-series isochron date of 89±10 ka on a travertine layer separating Acheulian layers from the lowest Mousterian bed; layer 23. We have obtained electron spin resonance (ESR) ages on tooth enamel from the immediately overlying Mousterian-bearing layers 22 and 21, yielding an average age for the two layers of 70±8 ka. Early and linear uptake ages are indistinguishable, due to low uranium contents in the teeth. This age is consistent with the age for the underlying travertine. Assuming a constant deposition rate, this age is also consistent with the c . 40 ka age for the overlying early Aurignacian layer 18.

A new method of calculating beta doses for one-dimensional geometries, based on “one-group” theory, is presented. In typical situations it is found that this approach leads to average beta doses which are significantly lower (by up to 50%) than those from Grun's DATA software. For various natural sources, our beta dose rate estimates are slightly greater than expected from calculations based on Monte Carlo data, while the DATA results agree well with the experimental results of Aitken et al. (1985) for the uranium and thorium decay chains. Further experimental evidence is desirable to resolve this issue. We compare age estimates calculated using new ESR dating software called ROSY, which incorporates this approach, with those from DATA. Because of the difference in beta dose estimates, ROSY ages are generally older than the corresponding DATA ages, there being little difference in gamma and alpha dose estimates. We do however observe significant discrepancies in cosmic dose estimates. Examination of results for El Castillo Cave, Spain, by Rink et al. (1996) suggests that the ROSY age estimates are the more accurate.

Many of the environments used for ESR and luminescence dating are inhomogeneous over the distances up to 0.3 m which contribute to gamma doses, and the consequent variability in gamma dose usually cannot be ascertained on a sample by sample basis. In this paper we examine the characteristics of such “lumpy” environments by simulation. Random environments were generated in which spherical source-free calcite inclusions were embedded in a source-rich sediment matrix. Using dose point kernels based on build-up factors, the gamma dose rate at a large number of random points in the sediment was then calculated. Various values for the sphere radius and volume fraction of the inclusions were tested. The gamma dose rate frequency distributions exhibit negative skewness, with the low outliers arising from points close to one or more inclusions. The variance of the distribution and the significance of the negative tail increase with the inclusion radius. Lognormal and gamma distributions were found to fit these histograms quite well. By sampling from the dose rate distribution, it was possible to repeatedly generate two hypothetical samples representing the positions of contemporaneous datable objects (and thus their accumulated doses) and of dose meters. Various statistical estimators were trialled to establish the optimum approach to extracting a site age from given sets of accumulated dose and gamma dose rate values. For ease of analysis, it was assumed that the gamma dose is the total dose, but the techniques can be generalised to realistic dose environments also. Most estimators produced values accurate to a few percent for typical environment parameters, and the one with the least variance was based on a two-stage maximum likelihood approach to age estimation. In the absence of such a sophisticated approach, culling of low valued outliers for both accumulated dose and dose rate leads to improved site age estimation.

The Ciuntu rockshelter is situated in the north-western part of the Republic of Moldova, on the left bank of the river Pruth. It has a single Upper Palaeolithic layer of occupation, which was originally regarded as Early Upper Palaeolithic and was assigned to the Brinzeni archaeological culture. More recent investigations, including radiocarbon dating, have led to a revision of this suggested age and classification. The site is now regarded as belonging to the Middle Gravettian and is dated to the beginning of the last glacial maximum.

In this study three sediment samples were used which came from two cave sites situated on the coast of Gibraltar, Gorham's Cave and Vanguard Cave. Both caves contain silts, sands and breccia deposits from the last interglacial through to the post-glacial period, from which beach sands were sampled for dating. The three sediment sample cores were each divided into two sub-samples, which were independently measured at McMaster University and Oxford University using quartz OSL. Similar sample preparation and measurement procedures were used at both laboratories, but different measurement equipment was employed in each. It was therefore hoped to identify any factors that may result in systematic differences between laboratories. The data showed very good agreement in results when a narrow wavelength band was used for stimulation, from either an argon-ion laser (514.5 nm) or a filtered halogen lamp (514±17 nm). This indicates that slight differences in factors such as laboratory lighting, measurement time, additive dose levels, detection filters, stimulation source and power did not produce differences in results. However, when a wide wavelength band from the halogen lamp was used for stimulation (440–560 nm) significantly different results were obtained, suggesting care needs to be taken with the waveband used.

Electron spin resonance (ESR) and mass spectrometric U-series dating has been carried out on teeth recovered from Kůlna cave during the excavations of 1961–76. Linear and early uptake (LU and EU) age estimates are similar due to low internal U content of the teeth. In general, ESR ages decrease upward in the section, but teeth from stone-rich (“lumpy”) layers give anomalously young ages, due to uneven dose-rate distribution. Elephant molars also give anomalously low ages, apparently due to self-absorption of gamma dose. Disregarding anomalous data, earliest appearance of Micoquian lithics and last occurrence of Dicerorhinus kirchbergensis in layer 9b is dated to 69±8 ka, which places them near the oxygen isotope stage (OIS) 5a/4 boundary. Neanderthal remains and the latest occurrence of Micoquian lithics in level 7a are dated to 50±5 ka, in good agreement with an uncalibrated radiocarbon date for this level of about 45 ka. The interstadial character of the fauna of this level also agrees with its date which places it in OIS 3. We also report that three stadial/interstadial cycles recognized in the lithological, faunal and palynological record of levels 9b through 7a at Kolna occurred during the timespan from about 70 to 50 ka.

At El Castillo, in Cantabrian Spain, uncalibrated AMS 14 C dating has shown the transition from Mousterian to Aurignacian to occur at 39·3±1·6 ka BP . We found ESR tooth enamel ages from the basal Aurignacian level at El Castillo to be 36·2±4·1 ka (early and linear uptake). The enamel and dentine had very low U contents, but ESR ages are strongly dependent upon knowledge of the moisture content history of the sediments. Although the Aurignacian ESR age is 8% younger than the weighted average uncalibrated AMS 14 C age of 39·6±1·3 ka obtained from charcoal samples, we have shown that the methods agree within experimental uncertainty. However, since no precise 14 C calibration yet exists for this period of time, we are unable to specify which of the ages is more accurate, nor are we able ascribe the apparent age discrepancy to a particular deficiency in the ESR method.

We performed ESR dating on tooth enamel from three in situ locations within the West Runton Freshwater Bed (FW) bed, which is stratigraphically below fluvial sands of Anglian origin. The teeth contained little uranium, which made ESR ages essentially independent of the choice of uranium uptake model. However, this advantage was offset by a critical dependence of the ESR ages upon the moisture content of the sediments. Care was taken to account for self-shielding effects arising from the large size of the elephant tooth. Using the value of 10% moisture content observed during 1992 in sediments exposed on the cliff face, gives ages of 346±55 (EU) and 350±52 (LU) ka, corresponding to the Oxygen Isotope Stage 11 10 boundary. Additional moisture content measurements of different parts of the FW bed in 1995 yielded a mean value of 25%. Using values of 20 and 30% moisture content, we obtain ages from 420±90 to 460±80 ka (EU, 1σ errors). Because the faunal and floral data indicate that the FW bed was an interglacial deposit, the ESR results suggest that the FW bed could have been deposited in either isotope stages 11 or 13. However, independent faunal and stratigraphic evidence favours a stage 13 age or earlier; this is discussed in relation to the ESR data. These results are consistent with prevailing views (e.g. Bridgland, 1994) that the overlying Anglian deposits correlate with oxygen isotope stage 12.

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/postinfrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabas¸, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations. "Natural Sciences and Engineering Council of Canada to WJR and MR (grant numbers not disclosed). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0054608

THE site of Longgupo Cave was discovered in 1984 and excavated in 1985–1988 by the Institute of Vertebrate Paleontology and Paleoanthropology (Beijing) and the Chongqing National Museum (Sichuan Province). Important finds include very archaic hominid dental fragments, Gigantopithecus teeth and primitive stone tools. Palaeomagnetic analysis and the presence of Ailuropoda microta (pygmy giant panda) suggested that the hominid-bearing levels dated to the earliest Pleistocene1. In 1992, joint Chinese–American–Canadian geochronological research corroborated the age using electron spin resonance (ESR) analysis. We report here that the hominid dentition and stone tools from Longgupo Cave are comparable in age and morphology with early representives of the genus Homo (H. habilis and H. ergaster) and the Oldowan technology in East Africa. The Longgupo dentition is demonstr-ably more primitive than that seen in Asian Homo erectus. Long-gupo's diverse and well preserved Plio-Pleistocene fauna of 116 species provide a sensitive contextual base for interpreting the early arrival of the genus Homoin Asia.

This article describes the essential features regarding the photo-stimulated luminescence of porcelain: both the main ceramic and glazing materials are studied. In each case, radiation dose dependent signals are observed, superimposed on dose independent luminescence transitions that are both Stokes and anti-Stokes shifted in energy. Glazing is shown in some cases to be considerably more sensitive as a radiation dosemeter than the main porcelain ceramic. By comparison with the properties of artificial phosphors, the principal luminescent matrix is identified as being Al 2 O 3 , and the recombination centres in one glazing type are shown to be F-centres, Cr 3+ and Dy 3+ .

We studied optical bleaching and gamma dose response of primary quartz isolated from volcanic and granitic host rocks as well as from pegmatites and hydrothermal veins using thermoluminescence (TL). We attempted to isolate the TL signature of these individual types of quartz so that improved analysis of the TL behaviour of composite sedimentary quartz mixtures is possible. We have identified the following aspects of quartz TL in these samples: (1) large variation in TL residuals after extensive bleaching; (2) shifts in glow curve peak temperatures during bleaching and gamma dose apparently related to 2nd order TL kinetics; (3) differences in TL sensitivity to gamma dose among samples; (4) supralinear dose response of both a 230°C TL peak and a germanium EPR signal only in the pegmatitic quartz samples; and (5) the volcanic and pegmatitic samples had generally higher TL sensitivity to gamma dose than did the granitic or hydrothermal samples. We concluded that (1), (2) and (3) could contribute to enhanced scatter in routine TL dating of sediments composed of mixed fractions of different quartz types, but that none of the effects observed appear to introduce any unforeseen sources of error into ED determinations using any of the standard sediment dating methods.

Electron paramagnetic resonance spectra and dose-response curves are presented for a variety of wallboard samples obtained from different manufacturing facilities, as well as for source gypsum and anhydrite. The intensity of the CO(3)(-) paramagnetic centre (G2) is enhanced with gamma radiation. Isothermal decay curves are used to propose annealing methods for the removal of the radiosensitive CO(3)(-) radical without affecting the unirradiated baseline. Post-irradiation annealing of wallboard prevents recuperation of the radiosensitive CO(3)(-) radical with additional irradiation. A single-aliquot additive dose procedure is developed that successfully measures test doses as low as 0.76 Gy.